Trace Amine-Associated Receptor 1 Displays Species-Dependent Stereoselectivity for Isomers of Methamphetamine, Amphetamine, and Para-Hydroxyamphetamine

Abstract

The synthetic amines methamphetamine (METH), amphetamine (AMPH), and their metabolite para-hydroxyamphetamine (POHA) are chemically and structurally related to the catecholamine neurotransmitters and a small group of endogenous biogenic amines collectively referred to as the trace amines (TAs). Recently, it was reported that METH, AMPH, POHA, and the TAs para-tyramine (TYR) and ␤-phenylethylamine (PEA) stimulate cAMP production in human embryonic kidney (HEK)-293 cells expressing rat trace amine-associated receptor 1 (rTAAR1). The discovery that METH and AMPH activate the rTAAR1 motivated us to study the effect of these drugs on the mouse TAAR1 (mTAAR1) and a human-rat chimera (hrChTAAR1). Furthermore, because S-(ϩ)-isomers of METH and AMPH are reported to be more potent and efficacious in vivo than R-(Ϫ), we determined the enantiomeric selectivity of all three species of TAAR1. In response to METH, AMPH, or POHA exposure, the accumulation of cAMP by HEK-293 cells stably expressing different species of TAAR1 was concentration-and isomer-dependent. EC 50 values for S-(ϩ)-METH were 0.89, 0.92, and 4.44 M for rTAAR1, mTAAR1, and h-rChTAAR1, respectively. PEA was a potent and full agonist at each species of TAAR1, whereas TYR was a full agonist for the rodent TAAR1s but was a partial agonist at h-rChTAAR1. Interestingly, both isomers of METH were full agonists at mTAAR1 and h-rChTAAR1, whereas both were partial agonists at rTAAR1. Taken together, these in vitro results suggest that, in vivo, TAAR1 could be a novel mediator of the effects of these drugs.

Pharmacological Characterization of Membrane-Expressed Human Trace Amine-Associated Receptor 1 (TAAR1) by a Bioluminescence Resonance Energy Transfer cAMP Biosensor

“…4D. Although among these compounds we detected no antagonist [based on their ability to counteract a ␤-PEA-induced BRET signal (data not shown)], we found several compounds that induced relatively potent agonist activity (Table 2) supporting previous reports on activity of these compounds at TAAR1 receptors (Bunzow et al, 2001;Miller et al, 2005;Reese et al, 2007;Wainscott et al, 2007;Wolinsky et al, 2007;. A list of compounds that exerted no activity at ␤TAAR1 in the BRET assay is presented in Table 3.…”

“…This poor cell surface expression has been a major limitation for understanding TAAR1 biology and evaluating TAAR1 selective ligands. In fact, up to this point, there has been no compelling direct evidence in the literature to suggest that the intact human TAAR1 could be expressed at sufficient amounts in a cell system, particularly at the plasma membrane compartment (Borowsky et al, 2001;Bunzow et al, 2001;Scanlan et al, 2004;Lindemann and Hoener, 2005;Miller et al, 2005;Grandy, 2007;Reese et al, 2007;Wainscott et al, 2007;Wolinsky et al, 2007;. Our data with HA-tagged and GFP-modified human TAAR1 provides evidence that glycosylation-stabilized expression of the receptor can occur in cells at levels sufficient for characterizing receptor biology and developing reliable in vitro cellular assays without modifying intracellular loops, developing human-rat chimeras (Lindemann and Hoener, 2005;Grandy, 2007), or coexpressing human TAAR1 with rat G␣ s (Wainscott et al, 2007).…”

“…The effects of amphetamine on behavior have historically been attributed to the release of internal stores of dopamine (Jones et al, 1998). However, recent observations indicated that amphetamine derivatives can also directly activate TAAR1 (Bunzow et al, 2001;Miller et al, 2005;Grandy, 2007;Reese et al, 2007;Wainscott et al, 2007;Wolinsky et al, 2007;. Therefore, by using the EPAC cell line, the ability of these two compounds to induce cAMP production through the ␤TAAR1 was tested (Fig.…”

“…TAAR1 is the best characterized of them (Borowsky et al, 2001;Bunzow et al, 2001;Grandy, 2007). TAAR1 couples to G s , and when assessed using cAMP, is activated by TAs such as ␤-PEA in addition to metabolites of catecholamines, amphetamines (including MDMA), and other compounds known to affect monoaminergic transmission (Borowsky et al, 2001;Bunzow et al, 2001;Kim and von Zastrow, 2001;Scanlan et al, 2004;Lindemann and Hoener, 2005;Miller et al, 2005;Grandy, 2007;Reese et al, 2007;Wainscott et al, 2007;Wolinsky et al, 2007;.…”

The Trace of Non-classical Biogenic Amines: A New Road to Addiction Recovery

“…The effects of methamphetamine on dopamine uptake require the interaction of methamphetamine with TAAR1 [27], suggesting that this novel receptor could contribute to the long-lasting pathophysiological neuroadaptations produced by psychomotor stimulants. The possible implication of TAAR1 in the psychopharmacological effects of stimulant drugs is further reinforced by the fact that several psychoactive substances, including amphetamine, methamphetamine, MDMA (3,4-methylenedioxymethamphetamine), and lysergic acid diethylamide are themselves agonists of TAAR1 [18,28].…”